Water coolers are as common in the work place as copy machines, yet copy machines receive maintenance and cleaning … most coolers do not.
Cooler Water Contamination
It is always interesting to watch how people handle the 5-gal. water bottles. First, they remove the sanitary top, then grab the neck sometimes touching the mouth of the bottle, and hoist it onto the cooler. Unfortunately, most are never conscious of the contamination they have just contributed by touching parts of the bottle that come in contact with the water.
It is not uncommon to find a cooler that is several years old and has never been cleaned. It is also quite common to inspect the reservoir and dispenser nozzles and find mildew and biofilm. And while I don’t want to focus on the importance of cooler sanitation, I can’t ignore the fact that coolers are a virtual gold mine for any conscientious service person.
Ask yourself what oxidizer can kill microbes quickly, impart no adverse taste or odor, can be tested and verified that it is present? The answer is, ozone.
The main objective when using ozone for water coolers is to maintain ozone residual in the water for a long enough period in order to kill bacteria. This can be done either on a periodic service cycle, or on a continuous treatment basis.
The main purpose of ozonating water coolers includes:
- Improving taste;
- Increasing storage life;
- Maintaining a microbe-free environment; and
- Complying with Federal and local health regulations.
Sizing the ozone equipment is based upon only a few parameters:
- Maximum flow;
- Maximum storage volume; and
- Water quality.
Ozone Residual Ranges
There are two ranges that are to be achieved: 1) Mid-Range Ozone Residual - 1 gr/H per 5 gpm of bottling flow = 0.1 to 0.2 ppm-O3 residual; and 2) High-Range Ozone Residual - 3 to 6 gr/H per 5 gpm of bottling flow = 0.3 to 0.5 ppm-O3 residual. The ozone production from the ozonator is represented in grams per hour (gr/H). The ozone residual in the water is measured as ppm-O3 Mid-Range is the most common. It will maintain ozone residual, pass inspection, and maintain a bacteria-free environment. The High-Range will kill bacteria that is present. Care must be taken with the High-Range because if misapplied, too much ozone could impart a burnt plastic taste and odor to the water.
Along with dosage comes contact time. There are no regulations as to the time required, but in general, the worse the contamination, the longer the contact time. Visible slime may take three to 10 minutes to kill, while maintaining a clean system requires no contact time.
The are three basic system designs:
- Periodic storage tank cleaning;
- Continuous in tank treatment (atmospheric/non-pressurized tank type); and
- Continuous on demand treatment (no atmospheric storage tank).
Periodic storage tank cleaning is the most common method utilizing the ozone to simply clean an existing cooler. The cooler may have a pressurized or non-pressurized tank. It also may be necessary to manually remove any visible biofilm or mildew prior to ozonating.
Continuous in-tank treatment and continuous on-demand treatment installations are permanently mounted ozone units, which inject the ozone either into a pressurized tank or line, or into a non-pressurized storage tank. The ozone is injected on-demand or via a timer depending upon the usage and water quality.
Ozone systems can also be used as the pretreatment system to remove iron, sulfur, manganese, color, bacteria, taste and odor. This will keep your polishing systems such as RO, softeners and carbon filters from fouling.
In conclusion, because water coolers require extensive maintenance to ensure quality water, ozonating water coolers can help eliminate the service hassle and some of the main problems associated with water coolers.